Hi Alec,
I've been doing alot of the posting about dizzies. It's not that I have little experience with them, in fact I have quite alot of experience with them, American and British. The issue with the Lucas dizzy I have in my Midget is that it always seemed like the weak spot in the whole system and is also the hardest to check. The A-series engine has always seemed like a solid performer (despite consuming large amounts of oil) and the carbs, when rebuilt proper and maintained seem to be alright, but the diz has never been a friend of mine. On all the American cars that I have experience with, ignition timing is really easy to check. Generally the timing marks are on the top of the crank pulley with very visible pointers. You can stand looking down into the engine with a strobe in one hand and the other hand on the dizzy making slight adjustments until you get the timing spot on the specs. You can then do vac timing, advance timing, etc all very easily. However, this has never been the case for me with my Midget. There is no way to get a strobe on the timing marks AT ALL that anyone has ever mentioned to me (and I've asked anyone who knows anything about brit cars) because there is a frame crossmember that travels right in front of where the timing marks are located, which, in the genius of British engineering (no offense) is directly on the BOTTOM! I've wondered if perhaps it was set up that way so that you could strobe the car if it was on a rack but actually, the crossmember blocks the view even worse from below. So now, due to this design flaw, one is forced to compromise. In short term fixes, one can set the static timing and just assume that the advance curve is correct (but we all no what happens when you ass-u-me). Otherwise, for a long term fix one must find TDC, then fabricate some sort of pointer and affix it to the timing chain cover or somewhere on the top side of the engine and then make a mark on the pulley and hope that everything isn't starting off misaligned by a degree or two from the get-go. Then you throw into the mix all the loose tolerances that all the british parts were manufactured with and you have a whole circus of problems, noises, bugs, jingles, misses, etc. I have now part-for-part gone through my dizzy and it is still making noises above 2200RPM. The best I can figure is the sloppy wholes that that the pins fit into for the centrifugal advance. I've never had that sort of problem with an American diz but I can only speak from my own experiences.